Due to the unique physical and chemical merits including excellent electrical conductivity, superior chemical stability, and tunable carbon framework, two-dimensional (2D) porous carbon nanosheets have drawn increasing research interest and demonstrated promising potentials in various applications. However, regulating the nanostructure of 2D porous carbon nanosheets by facile and efficient strategies remains a great challenge. Herein, we develop a new strategy to construct Fe,N-codoped hierarchical porous carbon nanosheets (Fe-N-HPCNS) by using 2D Fe-Zn layered double hydroxides (Fe-Zn-LDH) as multifunctional templates. Fe-Zn-LDH could functionalize not only as 2D structure directing agents but also as ternary hierarchical porogens for micro-, meso- and macropores and in situ Fe dopants. This multifunctional templating strategy toward 2D porous carbon nanosheets can improve the utilization of templates and shows great advantages against conventional procedures that additional porogens and/or dopants are often needed.

Organic solar cells are a current research hotspot in the energy field because of their advantages of lightness, translucency, roll to roll printing and building integration. With the rapid development of small molecule acceptor materials with high-performance, the efficiency of organic solar cells has been greatly improved. Further improving the device efficiency and stability and reducing the cost of active layer materials will contribute to the industrial development of organic solar cells. As a novel type of carbon nanomaterials, carbon dots gradually show great application potential in the field of organic solar cells due to their advantages of low preparation cost, non-toxicity and excellent photoelectric performance. Firstly, the synthesis and classification of carbon dots are briefly introduced. Secondly, the photoelectric properties of carbon dots and their adjusting, including adjustable surface energy level structure, good film-forming performance and up/down conversion characteristics are summarized. Thirdly, based on these intrinsic properties, the feasibility and advantages of carbon dots used in organic solar cells are discussed. Fourthly, the application progress of carbon dots in the active layer, hole transport layer, electron transport layer, interface modification layer and down-conversion materials of organic solar cells is also reviewed. Finally, the application progress of carbon dots in organic solar cells is prospected. Several further research directions, including in-depth exploration of the controllable preparation of carbon dots and their application in the fields of interface layer and up/down conversion for improving efficiency and stability of device are pointed out.

Liquid electrolytes used in lithium-ion batteries suffer from leakage, flammability, and lithium dendrites, making polymer electrolyte a potential alternative. Herein, a series of ABA triblock copolymers (ABA-x) containing a mesogen-jacketed liquid crystalline polymer (MJLCP) with a polynorbornene backbone as segment A and a second polynorbornene-based polymer having poly(ethylene oxide) (PEO) side chains as segment B were synthesized through tandem ring-opening metathesis polymerizations. The block copolymers can self-assemble into ordered morphologies at 200 °C. After doping of lithium salts and ionic liquid (IL), ABA-x self-assembles into cylindrical structures. The MJLCP segments with a high glass transition temperature and a stable liquid crystalline phase serve as physical crosslinking points, which significantly improve the mechanical performance of the polymer electrolytes. The ionic conductivity of ABA-x/lithium salt/IL is as high as 10⁻³ S·cm⁻¹ at ambient temperature owing to the high IL uptake and the continuous phase of conducting PEO domains. The relationship between ionic conductivity and temperature fits the Vogel-Tamman-Fulcher (VTF) equation. In addition, the electrolyte films are flame retardant owing to the addition of IL. The polymer electrolytes with good safety and high ambient-temperature ionic conductivity developed in this work are potentially useful in solid lithium-ion batteries.

The mixing morphology control plays a crucial role in photovoltaic power generation, yet this specific effect on device performances remains elusive. Here, we employed computational approaches to delineate the photovoltaic properties of layered heterojunction polymer solar cells with tunable mixing morphologies. One-step quench and two-step quench strategies were proposed to adjust the mixing morphology by thermodynamic and kinetic effects. The computation for the one-step quench revealed that modulating interfacial widths and interfacial roughness could significantly promote the photovoltaic performance of layered heterojunction polymer solar cells. The two-step quench can provide a buffer at a lower temperature before the kinetic quenching, leading to the formation of small-length-scale islands connected to the interface and a further increase in photovoltaic performance. Our discoveries are supported by recent experimental evidence and are anticipated to guide the design of photovoltaic materials with optimal performance.

Many cell-matrix interaction studies have proved that dynamic changes in the extracellular matrix (ECM) are crucial to maintain cellular properties and behaviors. Thus, developing materials that can recapitulate the dynamic attributes of the ECM is highly desired for three-dimensional (3D) cell culture platforms. To this end, we sought to develop a hydrogel system that would enable dynamic and reversible turning of its mechanical and biochemical properties, thus facilitating the control of cell culture to imitate the natural ECM. Herein, a hydrogel with dynamic mechanics and a biochemistry based on an addition-fragmentation chain transfer (AFCT) reaction was constructed. Thiol-modified hyaluronic acid (HA) and allyl sulfide-modified ε-poly-L-lysine (EPL) were synthesized to form hydrogels, which were non-swellable and biocompatible. The reversible modulus of the hydrogel was first achieved through the AFCT reaction; the modulus can also be regulated stepwise by changing the dose of UVA irradiation. Dynamic patterning of fluorescent markers in the hydrogel was also realized. Therefore, this dynamically controllable hydrogel has great potential as a 3D cell culture platform for tissue engineering applications.

Supramolecular adhesives that enable debonding on-demand are of significant research interest for the development of adaptive and smart materials, yet, biodegrable supramolecular adhesives have been rarely exploited. Herein, telechelic, three-armed and four-armed CO₂-based polyols with close molecular weights and various CO₂ content (or carbonate unite content) have been synthesized via a zinc-cobalt double metal cyanide complex catalyzed ring-opening copolymerization of CO₂ and propylene oxide, and further exploited as sustainable and biodegradable building blocks for supramolecular polymers (SMPs) with 2-ureido-4[1H]-pyrimidinone (UPy) motifs. Notably, the orthogonal modulation of the CO₂ content and the topology of CO₂-based polyols provide a unique opportunity to fine-tune the surface energy as well as the cohesive strength of the resulting CO₂-based SMPs. Notably, a three-armed SMP with 44% CO₂ (3UPy-CO₂-44%) can well balance the trade-off between surface energy and cohesive strength, therefore bestowing a high adhesive strength of 7.5 and 9.7 MPa towards stainless steel and wood substrates respectively by testing the corresponding single lap joints. Moreover, the light-responsive adhesion property of 3UPy-CO₂-44% has been demonstrated exemplarily by blending with a UV sensitizer.

Polymerization-induced chiral self-assembly (PICSA) is an efficient strategy that not only allows the construction of the supramolecular chiral assemblies in a controlled manner but also can regulate the morphology in situ. Herein, a series of azobenzene-containing block copolymer (Azo-BCP) assemblies with tunable morphologies and supramolecular chirality were obtained through the PICSA strategy. The supramolecular chirality of Azo-BCP assemblies could be regulated by carbon dioxide (CO₂) stimulus, and completely recovered by bubbling with Ar. A reversible morphology transformation and chiroptical switching process could also be achieved by the alternative 365 nm UV light irradiation and heating-cooling treatment. Moreover, the supramolecular chirality is thermo-responsive and a reversible chiral-achiral switching was successfully realized, which can be reversibly repeated for at least five times. This work provides a feasible strategy for constructing triple stimuli-responsive supramolecular chiral nano-objects in situ.

A selenium-functionalized ε-caprolactone was synthesized by introducing a phenyl selenide group at the 7-position. A polymer was obtained through the ring-opening polymerization of this monomer in a base/thiourea binary organocatalytic system. A living polymerization process was achieved under mild conditions. The resulting polymers had a controlled molecular weight with a narrow molecular weight distributions and high end-group fidelity. Random copolymers could be obtained by copolymerizing this monomer with ε-caprolactone. The thermal degradation temperature of the obtained copolymers decreased with the increasing molar ratio of selenide functionalized monomer in copolymers, while the glass transition temperature increased. In addition, the phenyl selenide side group could be further modified to a polyselenonium salt, which resulted in a polymer with good antibacterial properties. The survival rate of E. coli and S. aureus was only 9% with a polymer concentration of 62.5 μg/mL.

A series of non-isocyanate linear high molecular weight poly(ester urethane)s (PETUs) were prepared through an environmentally-friendly route based on dimethyl carbonate, 1,6-hexanediol and 1,6-hexanediamine. In this route, the polyurethane diol was first prepared by the reaction between bis-1,6-hexamethylencarbamate (BHC) and 1,6-hexanediol. A series of polyester soft segments of polyurethane have been synthesized from the polycondensation of adipic acid and different diols, including butanediol, hexanediol, octanediol and decanediol. The subsequent polycondensation of polyurethane diol and polyester diol led to linear PETUs. The resultant polymers were characterized by GPC, FTIR, ¹H-NMR, ¹³C-NMR, DSC, WAXD, TGA and tensile test. The results indicated that PETUs possess weight-average molecular weights higher than 1×10⁵ and the tensile strength as high as 10 MPa. The thermal properties, crystallization behavior, microphase separation behavior and morphology were studied by DSC and AFM, and the results indicated that the degree of phase separation was affected by two factors, the crystallization and hydrogen bonding interaction between soft segment and hard segment.

Payne effect and its associated weak overshoot are of importance for understanding and regulating the softening of rubber nanocomposites under large amplitude oscillations. Herein, Payne effect in diverse filled vulcanizates is investigated for generalizing the common characteristics. Master curves of strain amplitude dependent storage modulus are created with respect to microscopic strain amplitude of the matrix, revealing a matrix-dominated elastic nonlinearity being independent of type and dispersity of filler, crosslinking density and sol fraction of matrix and filler-rubber interfacial interactions. However, carbonaceous fillers with higher affinity to the rubber matrices yield lower strain amplification and higher overshoot behavior in comparison with siliceous silica. The investigation would be illuminating for preparing rubber nanocomposites with optimized reinforcement and softening performances.

Incorporating the surface-grafted cellulose nanocrystals (CNCs) with enantiomeric polylactide (PLLA or PDLA) is an effective and sustainable way to modify PLLA, but their difference in promoting matrix crystallization is still unrevealed. In this study, the CNCs with identical content and length of PLLA and PDLA (CNC-g-L and CNC-g-D) were prepared and blended with PLLA. The rheological properties of PLLA/CNC-g-D are greatly improved, indicating that the stereocomplexation can significantly improve the interfacial strength as compared with the conventional van der Waals force in PLLA/CNC-g-L. Surprisingly, the matrix crystallizes at a higher rate in PLLA/CNC-g-L than PLLA/CNC-g-D. PLLA/CNC-g-L15 reaches its half crystallinity in 8.26 min while a longer period of 13.41 min is required for PLLA/CNC-g-D15. POM observation reveals that the superior crystallization behavior in PLLA/CNC-g-L is originated from its higher nucleation efficiency and faster growth rate. The formation of low content of sc-PLA at the interface can restrict the diffusion of PLLA but contribute less to generate crystalline nuclei, which synergistically leads to the retarded crystallization kinetics in PLLA/CNC-g-D. Revealing the mechanism of different interfacial enantiomeric grafting on the melt rheology and crystallization of PLLA is of great significance for the development of high-performance polylactide materials.

To meet the processing requirements of resin transfer moulding (RTM) technology, reactive diluent containing m-phenylene moiety was synthesized to physically mixed with phenylethynyl terminated cooligoimides with well-designed molecular weights of 1500−2500 g/mol derived from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 3,4'-oxydianiline (3,4'-ODA) and m-phenylenediamine (m-PDA). This blend shows low minimum melting viscosity (<1 Pa·s) and enlarged processing temperature window (260–361 °C). FPI-R-1 stays below 1 Pa·s for 2 h at 270 °C. The relationship between the molecular weight of the blend and its melting stability was first explored. Blending oligoimides with lower molecular weights exhibit better melting stability. Upon curing at 380 °C for 2 h, the thermosetting polyimide resin demonstrates superior heat resistance (T_g=420−426 °C).